Carbon pile voltage regulator



Sept. 23, 1947. w. G. NEILD 2,427,805

WilliauwG. IVeild.

Sept. 23, 1947. w. G. NEILD 2,427,305

CARBON FILE VOLTAGE REGULATOR Filed Dec. 27, 1944 4 SheetsSheet Fig.2.;fg e ii 10 v A 16 1 V t r Fig-5- W95 OI still:

WI I" 66 gunman/(o0 William G. lveilab.

Sept. 23, 1947. w. G. NEILD 2,427,305

CARBON PILE VOLTAGE RBQULA'I'OK Filed Dec. 27, 1944 4 Sheets-Sheet 3INVE'VI'UIL yilliam a Arromvzv MIX-1 Sept. 23, 1947. w. a. NEILD2,427,305

CARBON FILE VOLTAGE REGULATOR Filed Dec. 27, 1944 4 Sheets-Sheet 4 5E:a. a \C i B a Pam mama 4/ P l I D 7110 J 090 .an m m .m an an o AIIIAD5mm Alma; Alb MACH? unsung; "I "all". m1 F All I... "If 50 1. 9 clunolnu musmmv 1"" MW i A i g I .2

w II I l 1' 5-2 mm. a fib M V f c-2 II I 1 l E ia-1| "ORR-our J m I I IIv I c -4 -nn- 5 1 8-! g m I m: Lmq new 26 J 6'2 g I mvuvmx. 5 w 7 BY .0W .Oma,

Patented Sept. 23, 1947 UNITED STATES PATENT OFFICE cannon PILE VOLTAGEREGULATOR Application December 27, 1944, Serial No. 570,002

8 Claims.

The present invention deals with electrical regulators and is concernedprimarily with regu1ators of the so-called carbon pile type.

At the present time carbon pile regulators have come into widespread usefor such purposes as controlling the voltage of the output of generatorsand also in the governing of current.

All of these carbon pile regulators operate on the principle of varyingthe pressure applied to the carbon pile; the range of effective pressureon the pile being the regulating range of the regulator.

There has now come into fairly widespread use a regulator which ischaracterized as including the usual carbon pile, one end of which isrelatively fixed. Operatively associated with the other end to applypressure on the pile, is an armature and this armature is carried by aspring of the leaf type having a plurality of spring fingers whichengage at the extremities thereof, an inclined abutment formed on theelectromagnet.

The force of the electromagnet is rendered effective on the armature,and the spring above referred to, tends to urge the armature towards thepile, while the magnetic force tends to withdraw the armature from thepile and to force the spring fingers into abutting relation along theinclined surface of the abutment provided on the electromagnet so as toapproximately vary' the force exerted by the spring inversely as thesquare of the distance between the armature and magnet so as to effectbasic correspondence with varying magnet full results.

With carbon pile regulators of this type considerable mechanicaldifficulty has been experienced in obtaining desired regulating effectsdue to the difficulties incident to calibrating the several springfingers to the inclined abutment, so as to give the effect desired.Moreover, the latter spring has a characteristic which outside itsnormal limited working range and with lower forces is quite differentfrom that within its limited working range. Thus upon wear of the carbonpile which inevitably results through use, this latter characteristicoften results in high voltage and consequent failur of control anddamage to the electrical system.

An object of the present invention, therefore, is to simplify andimprove the aforenoted spring construction.

Another object of the invention is to provide a novel leaf springconstruction having a first spring surface inclined at an angle to afirst abutment surface provided on an armature plate and a second springsurface inclined at an angle to a second abutment surface and the saidspring surfaces being so arranged as to wrap upon the respectiveabutment surfaces so as to substantially vary the force exerted by thespring on the carbon pile approximately inversely as the square of thedistance between the armature and magnet so as to effect basiccorrespondence with varying magnet pull results.

Another object of the invention is to provide 5 a novel leaf springarranged to wrap upon the under surface of an armature plate so as toprovide the desired regulating effect.

Another object of the invention is to provide a novel springconstruction having a relative wide operating range so as to compensatefor severe wear of the carbon pile and thereby prevent a rise in voltageunder such conditions.

Another object of the invention is to provide a novel mounting for thearmature including a leaf spring forming a frictionless hinge for thearmature and having an end portion wrapping upon an abutment surface soas to progressively increase the resistance of said spring todisplacement of the armature by an electromagnet.

Another object of the invention is to provide a novel ring providing amounting means for the armature and having an inner wall surface formingan abutment for the spring, and said ring being formed of a materialhaving a relatively high coefficient of expansion so that the expansionnd contraction of the ring due to changes in temperature will adjust thespring through the abutting surface of the inner wall so as tocompensate for those changes in the resistance of the carbon pile and inelectromagnetic force act ing upon the armature due to change in theresistance of the electromagnetic winding caused by variations intemperature.

Another object of the invention is to provide a novel armature, leafspring and mountin ring assembly whereby one end of the leaf spring isfastened to the ring and armature in such a manner as to form africtionless hinge for the armature, while the other end is preformed sothat when assembled a first portion of the end lies tangent to theperpendicular inner wall surface of the ring, while a second portion ofthe spring lies tangent to the horizontally extending under surface ofan armature plate. The leaf spring is further so arranged that anelectromagnetic force applied to the armature against the biasin forceof the leaf spring causes the points of tangency of the leaf spring tomove up the inner wall surface of the mounting ring and 50 out the undersurface of the top plate of the armature so as to progressively increasethe resistance of the spring to displacement of the armature.

Another object of the invention is to provide 55 a main leaf spring anda novel auxiliary leaf spring so arranged in relation to the main leafspring as to change the spring rate acting upon the armature.

Another object of the invention is to provide 60 a novel main spring forcounteracting the bias- 3 ing force of an electromagnet on an armature,and an auxiliary spring acting upon said armature jointly with said mainspring within a predetermined operating range.

Another object of the invention is to provide on the regulating spring anovel dynamic vibration damping means, including two pendulous weightsmounted at opposite sides of the armature by spring hinges so as tominimize the effects of severe external shocks.

These and other objects and features of the invention are pointed out inthe following description in terms of the embodiments thereof which areshown in the accompanying drawings. It is to be understood, however,that the drawings are for the purpose of illustration only, and are notdesigned as a definition of the limits of the invention, reference beinghad to the appended claims for this purpose.

In the drawings, wherein reference numerals refer to like partsthroughout the several views:

Figure 1 is a longitudinal sectional view of the carbon pile regulatorconstructed in accordance with the present invention with certain partsbroken away to better illustrate the novel leaf spring structure.

Figure 2 is a modified form of the invention of Figure 1.

Figure 3 is a fragmentary view of Figure 1 showing the operation of thenovel leaf spring as the armature is forced toward the electromagnet.

Figure 4 is a top plan view of the spring assembly of Figure 1 andsomewhat reduced in size.

Figure 5 is a perspective view of the novel leaf spring illustrating themanner in which the wrapping end portions of the spring is preformed.

Figure 6 is a top plane of a third modified form of the novel springassembly.

Figure 7 is a perspective view of the novel spring used in the form ofthe invention shown in Figure 6.

Figure 8 is a fragmentary sectional view taken along the lines 8-8 ofFigure 6.

Figure 9 is a fragmentary view illustrating the mode of operation of thenovel spring of Figure 6.

Figure 10 is a view of Figure 11 illustrating the wrapping action of thenovel spring on the under horizontal surface of the top plate.

Figure 11 is a fragmentary view illustrating the manner in which the endof the spring is preformed.

Figure 12 is a view illustrating graphically a comparison between thespring characteristics of the several leaf springs herein described.

Figure 13 is a. view illustrating graphically the effect on theregulated voltage of variance in the adjustment of the carbon pile bywear or other causes.

Referring to Figure 1, it will be seen that there is provided a frame Ihaving attached thereto by screws 2 a plate 3. Screw threadedly aifixedto the plate 3 is a magnetic core 4 which projects through anelectromagnet winding 5 also carried by the plate 3. The core 4 isfastened in position by screws 6. A casing I encloses the electromagnetand a suitable annular member I5 isfreely mounted upon the casing |0permitting a limited expansion and contraction of the member I5 inresponse to changes in temperature. The member I5 is preferably in theform of a die cast aluminum ring having a relatively great temperaturecoefllcient of expansion.

The annular member 5 is fastened to the plate 3 through suitable screwsI6, one of which is shown in Figure 1. The screws l6 project freelythrough openings H in the ring I5. Screws I9 extend freely throughopenings 20 formed in a plate 2|, one of which is shown in Figure 1,into screw threaded engagement with ring IS. The screws I9 are fastenedat the opposite end by nuts 23. The screws I9 are preferably formed of amaterial having a very low temperature coefficient of expansion and maybe formed for instance, of the nickel iron alloy sold under the tradename of Invar.

Formed integral with the plate 2| is a carbon piie housing 24 havingheat radiating fins 25. The housing 24 has a flange 25 provided at theopposite end from the plate 2|. The ring I5 is formed with an annularrecess or cylindrical boss 21 disposed within an annular recess orchamfered end portion 28 of the flange 28 and in circumspaced relationtherewith to permit radial contraction and expansion between the boss 21of the ring I5 and the chamfered end portion 28 of the flange 26 withouteffecting a clrcumbinding thereof. The flange and ring are furtherdisposed in sufficient spatiality to preclude engagement of the adjacentface of the ring with the flange of the housing upon longitudinalexpansion of the housing in response to a rise in temperature.

It will be noted, however, that since the rods I9 have a very lowtemperature coemcient of expansion, the distance between the plate 2|and the ring I5 will remain relatively constant, since the same arefastened in spaced relation by the rods l9.

Fastened to the plate 2| at the exterior surface thereof by suitablescrews, not shown, is a second plate 30. The plate 35 is insulated fromthe plate 2| by a suitable insulating member 3|. There is fastened tothe plate 30 by a bolt 35 and nut 35, a cap 31 in which is screwthreadedly engaged a screw 40 locked in position by a suitable fiatspring lock indicated by the numeral 39. The screw 40 has a cleftportion 4| accessible from the exterior.

An electrical conductor 42 is connected to the cap 31 by the nut 36 andthrough the cap 31 to the nut 40. Mounted in the housing 24 andextending longitudinally therein is a non-conducting tube 45 of asuitable refractory material, such as porcelain. Tube 45 is retained inplace by a member 48 engaged in a groove 49 formed in the tubular member45. The member 48 is attached to the plate 2| by a screw 50. The tubularmember 45 carries carbon discs 55 forming a carbon pile. Contactormembers 56 and 51 are positioned at opposite ends of the carbon pile 55.

The screw 40 is turned so as to adjust the contactor 55 and thereby theinitial contact pressure between the carbon discs 55.

The contactor 51 provided at the opposite end of the carbon pile 55 ismounted in a cup shaped securing member 60 formed in an electricalconductor plate 6|. An electrical conductor 62 leads from the conductorplate 6|.

The conductor plate GI and the contactor 51 is biased under force of anovel spring biased armature plate assembly indicated generally by thenumeral 55 in a direction toward the carbon pile 55.

The novel spring biased armature, plate assembly, includes a top plate65 and bottom plate 61 positioned at opposite sides of a novel leafspring I formed of a. suitable material and preferably a spring steelhaving a relatively low temperature coefficient of expansion. The topplate 65, bottom plate 61 and leaf spring III are fastened to anarmature 15 by bolts 16. The plate is attached by screw 18 to the topplate 66, bottom plate 61, spring and armature l5 and is insulatedtherefrom by insulating plate 19, insulating bushing 80, and washer 8|.Separating the magnet case in and ring I5 across the air gap between themagnet 4 and armature extends a suitable non-magnetic member 83preferably formed of brass for providing means for limiting the minimummagnetic gap between the armature and magnet case to prevent sticking ofthe armature 15 at the extreme minimum air gap position.

The novel leaf spring I0, shown in Figure 1, is clamped at one end by abar 85 and securing screws 86 to the annular member I5, as shown inFigure 4, so as to form an antifrictional hinge for the armatureassembly.

The novel leaf spring 10, as shown in Figure 5, has the opposite endportion 90 preformed with two gradual curved bends at 9| and 92, thebend at 9| being formed with a greater radius than the bend at 92.

The novel leaf spring 10 is positioned in the annular ring I5 so that anend portion 95 rests upon the horizontal surface of the member 83, whilethe surface between the end 95 and the bend 92 lies either tangentiallyalong the vertical inner wall surface of ring l5 or at an angle thereto,depending upon the compressive force applied to the spring 10. Likewise,the surface between the bend 92 and 9| lies either tangentially alongthe under surface of the top plate 56 or at an angle thereto, dependingupon the compressive force applied to the spring 10.

As the electromagnetic force of the electromagnet 5 increases, thearmature 15 is drawn toward the core 4 decreasing the air gap betweenthe core 4 and the armature 15. As the force thus exerted on thearmature 15 increases, the end portion 90 of the spring 10, wraps alongthe inner surface of the ring l5 and along the under surface of the topplate 66, as shown in Figure 3.

The end portion 90 of the spring 10 thus wraps upon the abutment surfaceprovided by the inner surface of the ring I5 and the under surface ofthe plate 56, and the length of the portion 90 of the spring 10subjected to further bending as the armature 15 moves further toward theelectromagnet 5, continuously decreases. The spring thus shortens andbecomes stiffer as the length of the air gap between the armature 15 andelectromagnet 5 lessens. Through appropriate design of the portion 90 ofthe spring "ill in relation to the abutment surfaces, the resistance ofthe spring 10 may be readily made to approximately vary inversely as thesquare of the distance between the point of application of the magnetpull to the spring and some fixed datum point which corresponds with thezero length of air gap. Except for the relatively small force needed toadjust the pile through adjustment screw 40 the total pull of the magnet5 balances the pressure exerted by the spring Ill.

The regulator of the present invention is particularly adapted for useas a regulator to maintain a constant voltage in a circuit. As anexample, the carbon pile 55, as is well known in the art, may beconnected through the conductors 42 and 62 in series with a shunt fieldwinding of a generator, while the winding 5 of the electromagnet isconnected in series with an adjustable ballast resistance across theoutput terminals of the generator. Thus if the voltage at the outputrises, the electromagnet 5 adjusts the armature 15 so as to decrease thepressure on the pile 55, increasing the electrical resistance of thepile 55 so that the field is reduced and the output voltage is reducedto the desired value. A decrease in the voltage at the output wouldcause an opposite effect, increasing the voltage to the desired value.

Thus variations in the regulated voltage will effect the magnet 5 toadjust the carbon pile 55 through the leaf spring 10 and armature 15 soas to vary the resistance afforded thereby and maintain the regulatedvoltage at the desired constant value. The novel spring Ill willprogressively increase the resistance of said spring to displacement ofthe armature 15 toward the electromagnet 5.

It will be further noted that an error may be introduced into theregulator due to the effects of variations in temperature upon theresistance of the carbon pile 55 and the resistance of the electromagnetwinding which preferably, is wound of copper wire. In order to eliminatethe latter errors there has been provided the annular member l5 having agreater temperature coefficient of expansion than the spring 10 mountedtherein. Thus upon an increase in temperature radial outward expansionof the member [5 will be effected, decreasing the pressure setting ofthe spring 10 so as to compensate for a decrease in the electricalresistance of the carbon pile 55 and a decrease in the biasing force ofthe electromagnet 5 for a given voltage. The latter decrease in theforce of the magnet 5 may be effected by an increase in the resistanceof the copper winding due to an increase in temperature. A decrease intemperature would, of course, have an opposite effect upon the carbonpile 55, copper winding of the electromagnet 5 and the annular memberl5.

Since a rise in temperature will effect a decrease in the resistance ofthe carbon pile 55, it will be readily seen that the annular member l5will also compensate for the effect of temperature variations on thecarbon pile 55 by varying the tension acting on the carbon pile 55 inresponse to temperature change.

In Figure 2, there has been shown a modified form of the invention inwhich like numerals indicate like partsto those previously describedwith reference to Figure 1.

In the latter form of the invention there is provided an auxiliary leafspring I00 positioned between the main leaf spring 10 and the top plate66 and attached to the armature I5 by the bolts 16 and 18. One end ofthe auxiliary leaf spring 10 is clamped to the annular member i5 by thebar and screws 85.

The opposite end portion illi of the auxiliary leaf spring I00 extendsat an angle to the under side of the top plate 66 and is bent on such aradius as to bear upon the end portion of the spring 10 to effect adesired increase in the spring resistance to movement of the armature 15within a minimum electrical resistance range of the pile 55 and therebydecrease the minimum electrical resistance of the pile 55 within thelatter regulating or operating range.

Thus within such operating range, the auxiliary leaf spring i0i effectsa change in the spring rate acting upon the armature 15. As the armature I5 approaches the zero air gapposition the leaf spring 15 wrapsalong the inner surface of the annular member 15 and the auxiliaryspring ill, compressing the spring iiil toward the top plate 55 againstthe tension thereof so that at the high electrical resistance end-of thecarbon pile 55, the auxiliary spring I50 has no effect. Through thislatter arrangement there is provided a spring characteristic, wherebyupon movement of the armature I5 towards the maximum air gap position, abiasing force is produced which more nearly approaches the forceproduced by the electromagnet 5 plus the pile force, which latterforcebecomes quite large within the minimum electrical resistance operatingrange as compared with a relative low pile force within the maximumelectrical resistance operating range.

In this connection, it should be noted that for ideal operatingconditions the force exerted by the leaf spring 10 of Figure 1 or thecombined forces of the main leaf spring 10 and the auxiliary leaf springllii of Figure 2 acting upon the armature 15 should equal the counterbalancing biasing force of the electromagnet 5 plus the inherent biasingforce of the carbon pile 55 at the desired regulated voltage. If theforce exerted by the spring means 10, or 15 and llil exceeds the forceexerted on the armature 15 by the electromagnet 5 and the carbon pile 55at the desired regulated voltage, it will be readily seen that the forceof the spring means will cause a further biasing force to be exerted onthe carbon pile 55 decreasing the electrical resistance thereof so as tocause a regulated voltage above the desired value. However, if the forceexerted by the spring means be less than the force exerted on thearmature 15 by the electromagnet 5 and carbon pile 55 at the desiredregulated voltage, it will be readily seen that the force of theelectromagent '5 will decrease the biasing force exerted on the carbonpile 55 below that required to efiect the desired voltage and therebyincrease the electrical resistance thereof, to cause a regulated voltagebelow the desired value.

As the armature I5, approaches the extreme open air gap position, it isdesirable to maintain the biasing force exerted by the spring" meansless than the force exerted by the electromagnet 5 at the predeterminedvoltage value, rather than in excess thereof, so as to assure aregulated voltage within the latter limited range less than thepredetermined constant voltage, but not in excess thereof.

Through this latter arrangement considerable wear of the carbon pile 55is permitted without excessive voltage conditions resulting. In thearrangement in Figure 1, this condition is provided by properlypositioning the left hand end of the under plate 61 in relation to thespring I and adjacent end of the top plate 55. It has been found that byadjusting the position of the under plate 51 toward the adjacent end ofthe top plate 56, the biasing force of the leaf spring ill in thislatter range is decreased. It is desirable to position the end of theunder plate 51 so that the latter biasing force of the spring 10 will beonly slightly less than that provided by the electromagnet for thedesired regulated voltage.

In the form of the invention shownin Figure 2, it will be readily seenthat as the armature 15 moves to the extreme open air gap position theend portion 90 of the spring is biased under the force of the end ililof the auxiliary spring I05, so that the end illl within the latterlimited operating range augments the biasing force of the leaf spring10. Thus within'the latter limited operating range of the leaf spring IIand auxiliary spring III, the force exerted by the spring II on thearmature II will more nearly approach a condition where the same willequal the force exerted by the electromagnet I plus the inherent biasingforce of the carbon pile 55 at the desired regulated voltage.

Moreover, in the forms of the invention shown in Figures 1 and 2, it hasbeen found desirable just beyond the maximum practical electricalresistance operating range of the carbon pile 55 to have the spring 15arranged so as to provide a biasing force in excess of that provided byelectromagnet 5, plus the inherent force of the carbon pile 55 at thedesired regulated voltage. The effect of this provision is that thespring 15 provides a snubbing action that resists adiustment of thecarbon pile 55 to a higher electrical resistance than the practicaloperating range of the carbon pile 55 by forces other than the regulatedforces, as for example external shocks.

In the form of the invention shown in Figure 2, there is also provided adust-tight cover ilil which encloses the armature assembly within theannular member i5. An annular groove H5 is provided in the member i5 forreceiving an annular edge of the cover cap iill positioned in a suitablesealing ring I IS. A suitable orifice H1 is formed in the cover cap forreceiving an end of the tubular member 45 of the carbon pile 55. Thecover cap H0 is fastened to the annular ring l5 by the bolts IS.

A third form of the invention is shown in Figures 6 through 10, inwhich, like numerals indicate like parts to those indicated in Figure 1.

In the invention shown in Figures 6, 7 and 5, there are provided on theleaf spring 15 laterally projecting ears or spring hinges I" to whichthere are riveted at opposite sides, suitable weights indicated by thenumerals I25 and ill. The weights I25. and I25 provide a dynamicvibration damping means to minimize the eifect of severe external shockson the regulator.

It will be further noted, that the leaf spring II is arranged, as shownin Figures 9 and 10, so as to wrap only on the surface of the leafspring between the bend 9i aid 92 along the under surface of the topplate 65 as the armature 15 moves toward the zero air gap position.Moreover, the leaf spring 10 is so arranged that the end 55 merelypivots at the junction of the inner wall of the annular member i5 andthe member 55 during the movement of the armature 15, without a wrappingaction along the inner surface of the annular member i5. However, by theproper selection of the spring Ill and position of the same in relationto the under surfaces of the top plate 55, a similar regulating effectmay be produced to that previously described with reference to Figure 1.

From the foregoing it will be readily seen that there has been provideda novel armature leaf spring assembly in which one end acts as africtionless hinge, while the other end portion is preformed, aspreviously explained, and arranged to wrap upon an abutment surface soas to progressively increase the resistance of the leaf spring todisplacement of the armature by eletromagnetic forces.

Moreover, there has been provided a novel spring assembly arranged tooperate upon severe wear of the carbon pile.

Moreover, there has been further provided a novel means for compensatingfor the effects on the regulator caused by changes in temperature.

Furthermore, in Figures 12 and 13 there has been illustratedgraphically, a comparison of the operating characteristics of the leafsprings hereinbefore described.

In Figure 12, the dotted line A indicates an approximation of an idealspring characteristic in which the spring force is always equal to thesum of the electromagnetic force plus the pile force at the desiredregulated voltage. Line B indicates a'regulator where the spring forceexceeds the sum of the pile force plus the magnetic force at the desiredregulated voltage as the armature approaches the maximum air gapposition. Line C indicates the spring characteristic of a regulator suchas shown in Figure 1 where there is provided a spring in which thespring force is loss than the sum of the forces exerted by the magnetand pile at the desired regulated voltage as the armature approaches themaximum air gap position. Thus in the latter device as the pile wears,the regulated voltage decreases, rather than increases as in the case ifa regulator having a spring characteristic such as indicated by the lineB. The line D indicates the effect of the second spring of Figure 2,which causes the spring force to more nearly approach the idealcondition indicated by line A.

Figure 13 illustrates graphically, by the lines B-I and B2, theoperation of a typical carbon pile regulator such as heretofore wellknown in the art, when used to control the shunt field of a generator soas to regulate the terminal voltage of the generator, as compared withthe operation of the novel regulator of the present invention, indicatedby lines C--l and C2 in regulating in a similar manner the terminalvoltage of such a generator.

The lines 3-! and B--2 indicate the effect on the terminal voltage byoperation of a carbon pile regulator having an armature spring withcharacteristics such as shown by line B of Figure 12, upon adjustment ofthe pressure acting on the carbon pile by wear or other causes asindicated graphically in Figure 13.

The lines Ci and C-2 indicate the effect on such terminal voltagethrough wear on the carbon pile of a regulator having an armature springwith a spring characteristic such as shown by line C of Figure 12.

The lines Bi and C-I indicate such effect under conditions of a fiftyampere load on the generator and lines 3-! and C2 indicate the effectunder no load conditions.

It will be readily seen that a decrease in the pressure exerted on thecarbon pile from the point of adjustment indicated on Figure 13,represents a comparable adjustment due to wear on the carbon pile.

The lines Bl, B2, C--l and C-2 illustrate graphically the carbon pilewear permitted Without detrimental rise in the regulated voltage by therespective regulators under the conditions specified.

It will be readily seen from Figure 13 that the novel regulator of thepresent invention allows greater wear or longer life without permittingthe regulated voltage to rise above allowable limits and with greaterstability of operation.

Although only three embodiments of the invention have been illustratedand described, various changes in the form and relative arrangement ofthe parts which will now appear to those skilled in the art ma be madewithout departing from the scope of the invention. Reference 10 istherefore to be had to the appended claims for a definition of th limitsof the invention,

What is claimed is:

1. In an electrical regulator of the type includ ing a variableelectrical resistance means, an electromagnet, an armature movablymounted in relation to said electromagnet, means connecting the armatureto the variable electrical resistance means, said electromagnet biasingsaid armature in a direction for increasing the electrical resistance ofsaid variable electrical resistance means; the improvement comprising aleaf spring, first and second plate members, said leaf spring fastenedbetween said first and second plate members and to said armature, anannular member mounted on said electromagnet, said leaf springpositioned within said annular member and extending diametrically acrosssaid annular member, one end portion of said leaf spring fastened tosaid annular member so that said leaf spring forms a flexible hinge forsaid armature, the other end portion of said leaf spring bearing uponsaid electromagnet and in such a manner that one part thereof extends atan angle to the inner surface of said first plate member and anotherpart thereof extends at an angle to the inner surface of said annularmember, said parts of said leaf spring wrapping tangentially upon saidsurfaces as said armature moves toward said electromagnet so as toprogressively increase the resistance of said leaf spring todisplacement of said armature by said electromagnet.

2. In an electrical regulator of the type including a variableelectrical resistance means, an electromagnet, an armature movablymounted in relation to said electromagnet, means connecting the armatureto the variable electrical resistance means, said electromagnet biasingsaid armature in a direction for increasing the electrical resistance ofsaid variable electrical resistance means; the improvement comprising a.leaf spring having a relatively low temperature coefficient ofexpansion, first and second plate members, said leaf spring fastenedbetween said first and second plate members and to said armature, anannular member mounted on said electromagnet, said leaf springpositioned within said annular member and extending diametrically acrosssaid annular member, one end portion of said leaf spring fastened tosaid annular member so that said leaf spring forms a flexible hinge forsaid armature, the other end portion of said leaf spring bearing uponsaid electromagnet and being formed in such a manner that one partthereof extends at an angle to the inner surface of said first platemember and another part thereof extends at an angle to the inner surfaceof said annular member, said parts of said leaf spring wrappingtangentially upon said surfaces as said armature moves toward saidelectromagnet so as to progressively increase the resistance of saidleaf spring to displacement of said armature by said electromagnet andsaid annular member formed of a material having a relatively greattemperature coefficient of expansion so that the position of the innersurface of said annular member varies with temperature for adjustingsaid leaf spring.

3. An electrical regulator, comprising, in combination, a variableelectrical resistance means, an electromagnet, an armature movablymounted in relation to said electromagnet, means connecting the armatureto the variable electrical resistance means, said electromagnet biasingsaid armature in a direction for increasing the elec- 11 tricalresistance of said variable electrical resistance means, a spring memberfor biasing said armature in an opposite direction for decreasing theelectrical resistance of said variable electrical resistance means, aring like element, said spring member positioned within said ring likeelement and extending diametrically across said element,

one end of said spring fastened to said element and the opposite endbearing on the inner surface of said element and resting upon theelectromagnet, and a portion of said opposite end of said springwrapping tangentially upon the inner surface of said ring so as toprogressively increas the resistance of said spring to displacement ofsaid armature by said electromagnet. 4. An electrical regulator,comprising, in combination, a variable electrical resistance means, anelectromagnet, an armature movably mounted in relation to saidelectromagnet, means connecting the armature to the variable electricalresistance means, said electromagnet biasing said armature in adirection for increasing the electrical resistance of said variableelectrical resistance means, a spring member for biasing said armaturein an opposite direction for decreasing the electrical resistance ofsaid variable electrical resistance means, a ring like element, saidspring member positioned within said ring like element and extendingdiametrically across said element, one end of said spring fastened tosaid element and the opposite end bearing on the inner surface of saidelement and resting upon the electromagnet, and a portion of saidopposite end of said spring wrapping tangentially upon the inner surfaceof said ring so as to progressively increase the resistance of saidspring to displacement of said armature by said electromagnet, and asecond spring for varying the spring rate of said first spring memberwithin a predetermined operating range.

5. An electric regulator comprising a carbon pile, an electromagnetmechanically attached to one end of said pile, an armature for saidelectromagnet, a flexible sheet metal spring member, means connectingsaid armature and spring together and to the other end of said pile, sothat movement of the armature towards the electromagnet is opposed bythe biasing force of said spring member, and the pile is subjected to acompressive force equal to the difference between the pull of theelectromagnet and the spring pressure, portions of said spring memberprojecting laterally from said member, and pendulous weight afllxed tosaid projecting spring portions and at opposite sides of the armature todampen the vibration of said spring member.

6. An electrical regulator, comprising, in combination, a variableelectrical resistance means, an electromagnet, an armature movablymounted in relation to said electromagnet, means connecting the armatureto the variable electrical resistance means, said electromagnet biasingsaid armature in a direction for increasing the electrical resistance ofsaid variable electrical resistance means, a spring member for biasingsaid armature in an opposite direction for decreasing the electricalresistance of said variable electrical resistance means, a hollowelement carried by the electromagnet and having an inner surface, saidspring member positioned within said hollow element and extending acrosssaid hollow element, one end of said spring fastened to said element andthe opposite end bearing on the inner surface of said element andresting upon the electromagnet, and a portion of said opposite end (Isaid spring wrapping tangentially upon the inner surface of said hollowelement so as to progressively increase the resistance of said spring todisplacement of said armature by said electromagnet.

7. An electrical regulator, comprising, in combination, a variableelectrical resistance means,

an electromagnet, an armature movably mounted in relation to saidelectromagnet, means connecting the armature to the variable electricalresistance means, said electromagnet biasing said armature in adirection for increasing the electrical resistance of said variableelectrical resistance means, a spring member for biasing said armaturein an opposite direction for decreasing the electrical resistance ofsaid variable electrical resistance means, a hollow element carried bythe electromagnet and having an inner surface. said spring memberpositioned within said hollow element and extending across said hollowelement, one end of said spring fastened to said element and theopposite end bearing on the inner surface of said element and restingupon the electromagnet, and a portion of said opposite end of saidspring wrapping tangentially upon the inner surface of said hollowelement so as to progressively increase the resistance of said spring todisplacement of said armature by said electromagnet, said spring memberhaving a relatively low temperature coefli'cient of expansion, and saidhollow element having a relatively great temperature coefficient ofexpansion so that the position of the inner surface of said hollowmember varies with temperature for adjusting said spring member.

8. An electrical regulator, comprising, in combination, a variableelectrical resistance means, an electromagnet, an armature movablymounted in relation to said electromagnet, means connecting the armatureto the variable electrical resistance means, said electromagnet biasingsaid armature in a direction for increasing the electrical resistance ofsaid variable electrical resistance means, a spring member for biasingsaid armature in an opposite direction for decreasing the electricalresistance of said variable electrical resistance means, a hollowelement carried by the electromagnet and having an inner surface, saidspring member positioned within said hollow element and extending acrosssaid hollow element, one end of said spring fastened to said element andthe opposite end bearing on the inner surface of said element andresting upon the electromagnet, said spring member having a relativelylow temperature coefficient of expansion, and said hollow element havinga relatively great temperature coefficient of expansion so that theposition of the inner surface of said hollow member varies withtemperature for adjusting said spring member.

WILLIAM G. NEILD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

